There are numerous ways to switch your opponent's monster to defense position, and many are easy to obtain cards outside of buying packs like Enemy Controller. This makes Drillroid a versatile card that can be put in many different decks since cards to switch to defense like Windstorm and Enemy Controller are common in most decks.
Some of the machine support cards are incredibly useful, making him fit well with a full machine type deck.
Pulse Mines switches all monsters your opponent controls to defense, as well any other monsters they might summon in the turn. This is really good since you can activate it when your opponent targets it with cards like Sergeant Electro, or Storm and it will still work on monsters they would summon.
Rare Metalmorph will let you negate a spell card that targets your monster, and also increases your attack. This is commonly used to negate Enemy Controller since most deck has 1 or more copies of it in the deck.
Gravity Blaster is to negate monster effects, including flip effects, and increase attack. It's a good support card to have for a machine deck.